1. Field of the Invention
The present invention relates to a method for etching a metal layer on a scale of nano meters, and more particularly, to a method for etching a metal layer on a scale of nano meters by controlling bias voltage at a voltage-biased micro tip.
2. Description of the Related Art
In a conventional nano-scale etching method using a micro tip, a strong mechanical load is applied to the micro tip so that the micro tip digs into underlying material. However, in the conventional nano-scale etching method, it is difficult to etch material into a desired shape or size and control the etching speed. The conventional nano-scale etching method using a mechanical load force is usually applied to a data storage technique.
There are other data storage techniques including a method of polarizing a ferroelectric material, a method of thermally transforming polymer, a method of transforming the phase of a magnetic material, a method of transforming the phase of a resistant material, and a method of transforming the phase of metal or semiconductor through oxidation. However, each one of these techniques have a few disadvantages in view of data recording time and data storage.
To solve the above-described problems, it is a feature of the present invention to provide a method for etching a metal layer on a scale of nano meters which is capable of freely controlling the shape and size of a pattern to be etched and the etching speed on a scale of nano meters with the use of a voltage-biased micro tip.
Accordingly, to achieve the above feature, there is provided a method for etching a metal layer on a scale of nano meters. The method includes preparing a substrate on which a metal layer is formed, positioning a micro tip over the metal layer, generating an electron beam from the micro tip by applying a predetermined voltage between the metal layer and the micro tip, and etching the surface of the metal layer into a predetermined pattern with the electron beam.
Preferably, the micro tip is moved relative to the metal layer during the etching of the metal layer. Preferably, the predetermined voltage is varied within a particular range of voltage and is used to control the degree to which the metal layer is etched.
Preferably, the substrate is a silicon substrate, the surface of which is formed of a silicon oxide layer, and the metal layer is formed of gold (Au) on the top surface of the silicon oxide layer.
Preferably, the predetermined voltage is between 12 volts and 25 volts, and the micro tip is negative-biased. Preferably, the micro tip is formed of silicon (Si) and the surface of the micro tip is coated with a titanium film.
Preferably, a load of  less than 100 nN is applied to the micro tip along with a predetermined voltage between the metal layer and the micro tip.
The etching method of this invention is used for making a data storage device.
These and other features of the present invention will be readily apparent to those of ordinary skill in the art upon review of the detailed description that follows.